EXCHANGE 


innivcreit?  of  Chicago 


The  Molecular  Rearrangement  of  Symmetrical 
Bis-Triphenylmethylhydrazine 


A  DISSERTATION 

SUBMITTED  TO  THE  FACULTY  OF  THE  OGDEN  GRADUATE 

SCHOOL  OF  SCIENCE  IN  CANDIDACY  FOR  THE 

DEGREE  OF  DOCTOR  OF  PHILOSOPHY 

DEPARTMENT  OF  CHEMISTRY 


BY 

RALPH  LYMAN  BROWN 


Private  Edition  Distributed  by 

THE  UNIVERSITY  OF  CHICAGO  LIBRARIES 

CHICAGO,  ILLINOIS 


Reprinted  from  the  Journal  of  the  American  Chemical  Society,  Vol.  44,  No.  6,  June,  1922. 


Gbe  inniversits  of  Chicago 


The  Molecular  Rearrangement  of  Symmetrical 
Bis-Triphenylmethylhydrazine 


A  DISSERTATION 

SUBMITTED  TO  THE  FACULTY  OF  THE  OGDEN  GRADUATE 

SCHOOL  OF  SCIENCE  IN  CANDIDACY  FOR  THE 

DEGREE  OF  DOCTOR  OF  PHILOSOPHY 

DEPARTMENT  OF  CHEMISTRY 


BY 

RALPH  LYMAN  BROWN 


Private  Edition  Distributed  by 

THE  UNIVERSITY  OF  CHICAGO  LIBRARIES 

CHICAGO,  ILLINOIS 


Reprinted  from  the  Journal  of  the  American  Chemical  Society,  Vol.  44,  No.  6,  June,  1922. 


EXCHANGE 


THE  MOLECULAR  REARRANGEMENT  OF  SYMMETRICAL 
BIS-TRIPHENYLMETHYLHYDRAZINE1 

Organic  hydrazine  derivatives  resemble  derivatives  of  hydroxyl- 
amine  in  all  fundamental  characteristics,  except  that,  with  a  single 
exception,  they  have  not  been  found  to  undergo  molecular  rearrange- 
ments of  the  same  type  as  the  Beckmann  rearrangement  of  oximes 
or  the  Lessen  rearrangement  of  hydroxamic  acids.  Stieglitz  and  Sen- 
ior,2 who  called  attention  to  this  difference,  made  a  series  of  a.t- 
tempts  to  effect  such  rearrangements  of  hydrazine  compounds,  but  all 
their  efforts  were  unsuccessful  except  when  they  used  sym.-bis-triphenyl- 
methylhydrazine,  (CeHs^C.NH.NH.CCCGl^a.  When  they  heated  this 
compound  to  250°  to  300°  with  anhydrous  zinc  chloride  and  hydrolyzed 
the  reaction  product,  aniline  was  obtained,  which  proved  conclusively 
that  one  of  the  phenyl  groups  of  the  triphenylmethyl  radicals  migrates 
under  these  conditions  from  carbon  to  nitrogen,  which  is  the  typical  shift 
of  the  Beckmann-Lossen  rearrangements,  and  of  the  analogous  rearrange- 
ments in  the  triphenylme thane  series  discovered  by  the  one  of  us  and  his 
collaborators.3  The  only  other  product  identified  in  the  preliminary 
investigation  was  triphenylmethane,  a  product  of  a  parallel  thermal  de- 
composition of  the  hydrazine. 

The  present  paper  reports  the  results  of  a  continuation  of  the  investi- 
gation, which  was  carried  out  to  throw  light  on  the  mechanism  of  the  re- 
arrangement. Unexpected  results  obtained  toward  the  end  of  the  in- 
vestigation have  made  it  impossible,  at  the  present  moment,  to  give  a  com- 
plete theory  of  the  reaction,  but  as  the  one  of  us  (Brown)  was  called 
to  service  in  the  U.  S.  Army,  we  wish  to  present  now  the  lines  of  thought 

1  This  paper  was  published  by  Ralph  L.  Brown  and  Julius  Stieglitz  in  the  /.  Am. 
Chem.  Soc.,  44,  1270-92  (1922). 

2  Proc.  Nat.  Acad.  Sci.,  1,  207  (1915);   and  J.  Am.  Chem.  Soc.,  38,  2727  (1916). 

3  See  the  literature  references  in  J.  Am.   Chem.  Soc.,  36,  272  (1914)  and  38,  2051 
(1916). 


O  O  i  O  *> 


followed  as  working  hypotheses  and  the  relation  of  the  results  obtained, 
to  these  views. 

By  analogy  to  other  rearrangements  of  this  type,  two  possible  courses 
of  the  rearrangement  reaction  are  suggested  at  the  outset.4  In  the  first 
place,  according  to  the  theory  of  the  one  of  us,5  we  might  have  as  the  primary 
action  offering  least  resistance  a  decomposition  of  the  hydrazine  compound 
into  triphenyl-methylamine  and  triphenyl-methylimide,  a  univalent  ni- 
trogen compound  which  would  undergo  the  rearrangement  proper 

I.  (C6H6)8C.NH.NH.C(C6H6)3  — +   (C6H6)3CNH2   +    (C6H5)3C.N          (1) 
and 

(C6H5)8C.N  — >   (C6H5)2C:NC6H6  (2) 

By  hydrolysis  of  the  phenylimido-benzophenone  thus  formed,  aniline 
and  benzophenone  would  be  produced. 

(C6H6)2C:  NC6H5  +  HOH  +  HC1  >   (C6H6)2CO  +  CeHsNHsCl        (3) 

The  alternative  course  of  the  reaction  would  be  a  rearrangement  akin 
to  the  rearrangement  of  triphenylmethyl-peroxide,   as  investigated  by 
Wieland.6 
(C6H6)3C.O.O.C(C6H6)8 — >2  (C6H6)3C.O >  2  (C6H6)2C.OC6H5  — >  (C6H6)2COC6H6 

(CflH6)2COC6H6    (4) 

#*s-triphenylmethylhydrazine  might  rearrange  in  an  analogous  way  as 
follows. 

II.     (C6H6)3CNH.NHC(C6H5)3  — >  2(C6H5)3C.NH  — >  2(C6H6)2C.NHC6H6 

(C6H6)2C.NHC6H5 

(C6H8)2C.NHC6H6  (5) 

Hydrolysis  of  the  resulting  product,  if  it  occurred  at  all,  would  lead  to 
the  formation  of  aniline  and  benzopinacone. 

[(C8H6)2C(NHC6H6)]2  +  2H20  +  2HC1  — >  [  (C6H6)2C(OH)  ],  +  2C6H5NH3C1  (6) 

In  the  experimental  part  of  this  report,  it  will  be  shown  that,  besides 
aniline,  which  was  again  identified  after  hydrolysis  of  the  reaction  prod- 
uct, benzophenone  was  isolated  and  identified,  a  result  which  decidedly 
favors  the  mechanism  of  the  reaction  expressed  under  I.  The  third  prod- 
uct of  the  reaction  required  by  Scheme  I  is  triphenyl-methylamine. 
This  was  not  found,  but  it  was  suspected  that  any  triphenyl-methylamine 
formed  would  be  decomposed  by  the  zinc  chloride  at  the  temperature  of 
the  reaction.  For  that  reason,  the  effect  of  zinc  chloride  on  the  amine  was 
studied.  As  anticipated,  when  triphenyl-methylamine  reacts  with  zinc 

4  The  interpretation  from  the  point  of  view  of  the  electron  conception  of  valence 
will  be  given  further  on  in  this  paper. 

6  See  the  literature  references  given  by  Stieglitz  and  Leech,  /.  Am.  Chem.  Soc.,  36, 
272  (1914)  and  by  Stieglitz  and  Stagner,  ibid.,  38,  2051  (1916). 

8  Wieland,  Ber.,  44,  2550  (1911). 


chloride,  the  chief  products  of  decomposition  are  ammonia,  phenyl-di- 
phenylenemethane  and  triphenylmethane.     For  instance,  we  may  have 

H 

I  /C6H4 
3  (C6H6)3C.NH2  — >  3NH,  +  2  C6H5C<  |         +  (C6H6)3CH  (7) 


This  action  is  analogous  to  the  decomposition  of  triphenylmethyl 
chloride  and  bromide  by  heat  and  of  the  corresponding  carbinol  by  phos- 
phorus pentoxide. 

Returning  now  to  the  examination  of  the  products  of  the  rearrange- 
ment of  fo'5-triphenylmethylhydrazine,  we  have  found  without  difficulty 
that  ammonia  and  phenyl-diphenylenemethane,  besides  triphenylmethane, 
are  indeed  formed  in  the  reaction.  Furthermore,  quantitative  determina- 
tions, which  will  be  discussed  at  greater  length  presently,  showed  that  the 
amount  of  ammonia,  i.  e.,  triphenyl-methylamine  as  the  primary  prod- 
uct formed  is  of  the  order  demanded  by  the  equations  given  under  I. 

Thus  far,  all  the  experimental  evidence,  therefore,  favors  the  conception 
that  the  rearrangement  of  fo's-triphenylmethylhydrazine  by  zinc  chloride 
follows  the  course  through  a  univalent  nitrogen  derivative  which  seems 
to  be  the  same  as  that  commonly  followed  as  the  path  of  least  resistance7 
in  the  rearrangement  of  oximes,  hydroxamic  acids,  chloro-  and  bromo- 
amides  of  the  acids,  acyl  azides,  triarylmethyl-azides,  -hydroxylamines 
and  -chloro-amines,  as  grouped  together  by  the  theory  of  the  one  of  us. 
Exhaustive  examination  of  the  reaction  products  brought  to  light  further 
facts,  some  of  which  have  raised  novel  and  interesting  questions.  Before 
these  are  presented,  it  seems  wisest  to  complete  the  discussion  of  the  re- 
arrangement proper  by  referring  as  briefly  as  possible  to  the  interpretation 
of  the  rearrangement  from  the  point  of  view  of  the  electron  conception 
of  valence.8  The  discussion  from  this  fundamental  point  of  view,  will 
greatly  facilitate  the  consideration  of  the  further  experimental  results 
to  be  presented  below. 

For  fo's-triphenylmethylhydrazine  we  have  the  electronic  structure9 
(C6H5+)J=C+  -N+-  N-  +C=(C6H5+)J  (8) 

+H        H  + 

The  atom  with  an  unstable  positive  charge,  as  postulated  by  the  one  of 
us  as  occurring  in  all  of  the  rearranging  compounds  of  this  character, 
in  the  present  instance  is  one  of  the  two  otherwise  apparently  symmetrical 
nitrogen  atoms:  for  the  sake  of  convenience  we  have  designated  the  un- 
stable nitrogen  atom  with  the  positive  charge  in  question  by  putting  it 
in  heavy  type  as  N+.  In  the  formation  of  a  rearranging  univalent  ni- 
trogen derivative,  either  of  the  following  courses  may  be  followed: 

7  Stieglitz,  Proc.  Nat.  Acad.  Sci.,  Ref.  2.     Stieglitz  and  Stagner,  Ref.  5. 

8  Stieglitz  and  Leech,  Ref.  5.     Jones,  Am.  Chem.  J.,  50,  440  (1913). 

9  Only  those  charges  are  indicated  which  bear  on  the  discussion. 


6 

(1)  the  true  ammonia  nitrogen  atom  ~Nl  deprives  the  nitrogen  atom  IN+ 
of  its  hydrogen  atom,  forming  triphenylmethyl-amine  (C6H5)3C.NH2 
and  triphenylmethyl-imide  (C6H6)3C .  Ni  which  by  a  shift  of  the  electron 
would  form  (C6H5)3C.N;  (2)  more  probably  the  disturbance  originates 
in  the  unstable  nitrogen  atom  IN+  which  captures  2  electrons  from  the 
neighboring  nitrogen  atom.  With  the  accompanying  migration  of  the  hy- 
drogen atom  lost  by  ~NI  as  a  result  of  the  loss  of  its  electrons,  this  gives 

(C6H5+)3^C+-NI(+H)2  and  N~+C  =  (C.H.+),  (9) 

As  a  basis  of  choice  between  these  two  possible  courses  we  have  no  experi- 
mental information  except  that  the  second  course  would  be  exactly  analo- 
gous to  the  changes  occurring  in  the  closely  related  rearrangements  of 
halogen  amides,  oximes,  etc.  A  final  decision  between  these  two  paths 
would  be,  we  believe,  of  great  importance,  since  therein  most  likely  will 
be  found  the  key  to  the  interesting  fact  that  this  symmetrical  hydrazine 
rearranges,  whereas  all  the  unsymmetrical  hydrazines  examined  by  Senior 
and  the  one  of  us  are  not  rearranged.10 

In  either  case,  we  have  then,  further,  the  normal  course  for  univalent 
nitrogen  rearrangements11 

(C6H6'+),  =  C+-N  — >  (C6H6+)2ZCj:rN-  — >  (C6H6+)2lCt:N-(C6H6+)     (10) 


^C6Hf 


C6H6  + 

Two  electrons  migrate  from  the  methyl  carbon  from  the  valence  indi- 
cated by  the  sign  in  heavy  type  to  the  univalent  nitrogen  atom,  the  released 
positive  phenyl  group  migrating  to  the  free  negative  charge  on  the  nitrogen. 

Returning  now  to  the  further  observations  made  in  the  course  of  the 
experimental  work,  we  would  mention  first  that  the  formation  of  tri- 
phenylmethane  and  nitrogen 

(C6H5)3C.NH.NH.C(C6H5)3  — >  N2  +  2(C6H6)3CH  (11) 

observed  by  Senior  and  the  one  of  us,  was  conclusively  shown  to  be  a 
thermal  decomposition.  The  electronic  interpretation  is  given  in  the  pre- 
liminary paper12  and  shows  that  the  decomposition  is  the  result  of  an  in- 
tramolecular oxidation-reduction  in  which  the  electrons  migrate  from 
the  nitrogen  to  the  methyl  carbon  atom,  whereas  the  molecular  rearrange- 
ment just  discussed,  which  is  also  the  result  of  an  intramolecular  oxida- 
tion-reduction reaction,  involves  a  migration  of  electrons  from  the  methyl 
carbon  to  the  nitrogen,  this  course  being  the  direct  reverse  of  that  followed 
in  the  thermal  decomposition.  The  decomposition  by  heat  and  the  re- 
arrangement are  therefore  the  results  of  two  parallel  and  competing  oxi- 

10  The  interpretation  is  given  by  Stieglitz  and  Senior,  Ref.  2  [/.  Am.  Chem.  Soc.\  p. 
2729.     Since  this  was  written,  Messrs.  E.  C.  Gilbert  and  J.  F  bmith  in  this  Laboratory 
have  effected  the  rearrangement  of  a  number  of  hydrazine  derivatives,  including  benzo- 
phenone-hydrazone.     (May,  1922). — J.  S. 

11  See  Stieglitz  and  Leech,  and  Stieglitz  and  Stagner,  Ref.  5. 
»  Ref.  2  (J.  Am.  Chem.  Soc.,  p.  2731). 


dation-reduction  reactions  of  an  intramolecular  character.  One  of  the 
main  experimental  difficulties  encountered  was  the  problem  of  reducing 
the  loss  of  material  by  the  thermal  decomposition  to  a  minimum.  At 
best  a  yield  corresponding  to  the  rearrangement  of  somewhat  more  than 
a  third  of  the  substance  was  finally  obtained. 

The  next  observations  made  were  not  anticipated  and  have  raised 
new  questions  of  interest.  Among  the  reaction  products  phenol  was  ob- 
tained in  appreciable  quantities.  It  was  at  first  thought  that  its  presence 
might  be  due  to  some  decomposition  of  the  aniline  group  hi  phenylimido- 
benzophenone,  the  zinc  chloride,  when  it  is  present  hi  large  excess,  possibly 
reversing  the  well-known  change  of  phenol  into  aniline  by  zinc-ammonium 
chloride.13  Experiments  made  with  phenylimido-benzophenone  and 
zinc  chloride  proved  that  this  is  not  the  source  of  the  phenol.  Nothing 
was  found  in  the  literature  indicating  "the  formation  of  phenol  from  tri- 
phenyl-methylamine  or  its  carbinol,  from  benzopinacone  (Equation  6) 
or  its  decomposition  product,  benzohydrol.  Furthermore,  it  was  then 
found  that  when  fo's-triphenylmethylhydrazine  is  heated  with  zinc  chloride 
in  the  absence  of  air,  for  instance  in  an  atmosphere  of  carbon  dioxide,  no 
phenol  is  formed,  but  the  formation  of  diphenyl  is  strongly  suggested  by 
its  odor.  The  carrying  out  of  the  action  in  the  presence  of  carbon  dioxide 
in  place  of  air  led  to  the  further  unexpected  observation  that  under  these 
conditions  there  is  no  rearrangement  to  an  aniline  derivative;  at  most, 
small  quantities  of  aniline  were  obtained  in  the  working  up  of  the  prod- 
ucts, which  might  be  due  to  the  presence  of  occluded  air  in  the  reagents 
used.  These  results  open  up  a  series  of  interesting  questions,  which 
can  only  be  suggested  here  as  the  basis  on  which  further  investigation  is 
being  planned. 

It  is  evident,  in  the  first  place,  that  the  production  of  phenol  is  due 
to  the  oxidation  of  a  phenyl  radical  at  some  stage  of  the  action  at  the  ex- 
pense ultimately  of  the  oxygen  of  the  ah-.  Two  interesting  possibilities 
suggest  themselves.  Phenol  may  be  formed  by  the  capture  of  oxygen 
by  some  of  the  phenyl  radicals  before  they  have  reached  their  destination, 
the  nitrogen  atoms  (see  the  middle  phase  of  the  action  represented  in 
Equation  10).  Whether  the  phenyl  radicals,  originally  positive,  first 
capture  some  of  the  migrating  electrons  which  lead  to  the  rearrangement, 
and  escape  because  they  have  become  electrically  neutral  is  a  matter  of 
fascinating  speculation  which  can  only  be  suggested  here.  In  support 
of  this  conception  we  have  the  fact  that  the  formation  of  diphenyl  is  indi- 
cated, as  yet  only  by  its  odor,  especially  when  oxygen  is  excluded.  As 
far  as  we  can  discover,  the  formation  of  compounds  of  the  type  of  phenol 
and  diphenyl  has  never  been  observed  before  in  the  numberless  rearrange- 
ments in  which  an  aryl  or  an  alkyl  group  migrates  from  carbon  to  nitrogen, 
18  Merz  and  Weith,  Ber.,  13,  1299  (1880). 


8 

but  none  of  these  has  been  carried  out,  as  far  as  we  can  find,  at  so  high  a 
temperature  as  300°. 

In  the  second  place,  Wieland14  found  that  when  azo-triphenylmethane 
is  formed  by  oxidation  of  fo's-triphenylmethylhydrazine,  it  decomposes 
at  once,  even  at  0°,  into  triphenylmethyl  :  this  compound  is  oxidized  by 
air  to  its  peroxide,  which  in  turn  is  rearranged  by  heat  into  the  diphenyl 
ether  of  benzopinacone  (Equation  4).  This  phenol  derivative  may  be  the 
source  of  the  phenol  obtained  in  our  reaction.  Wieland  found,  however, 
that  the  hydrazine  is  not  oxidized  to  the  azo  compound  by  air,  but  re- 
quires more  powerful  oxidizing  agents.  It  is  possible,  nevertheless,  that 
at  300°  a  temperature  never  attained  in  Wieland's  experiments,  oxidation 
by  air  does  occur.  Furthermore,  part  of  the  azo  compound  might  undergo 
the  rearrangement  leading  to  the  formation  of  phenylimido-benzophe- 
none,  as  follows. 

III.     (C6HS)3C.N.N.C(C6H5)3  +  O  —  *•  H20  +  (C6HS)3C.N:N.C(C6HS)3     (12) 

H  H 
and 

(C6H6)3C.N:N.C(C6H5)3  —  >  2(C6H5)3C.N  —  >  2(C6H5)2C:  NCCH5          (13) 

Electronically,  we  would  have 


+H      H+  +H20  (14) 

Two  electrons  leave  the  nitrogen  at  the  point  indicated  by  the  negative 
sign  in  heavy  type,  with  the  formation  of  water  and  azo-triphenylmethane. 
The  dissociation  of  the  latter  into  two  molecules  of  triphenyl-methylimide 
(C6H5)3C.N,  needs  no  further  explanation  and  the  rearrangement  of  the 
imide  would  follow  the  course  indicated  in  Equation  2  above. 

No  rearrangement  of  this  kind  was  ever  observed  by  Wieland  in  his 
attempts  to  prepare  azo-triphenylmethane,  and  while  the  reaction  which 
he  did  observe  (decomposition  into  nitrogen  and  triphenylmethyl)  was 
carried  out  in  the  cold  (usually  at  0°),  a  higher  temperature  would  pre- 
sumably simply  accelerate  this  decomposition.  Nevertheless,  some  of 
Wieland's  work  will  be  repeated  as  soon  as  circumstances  permit,  and 
efforts  especially  made  to  isolate  azo-triphenylmethane  in  order  that  it 
may  be  subjected  to  sudden  heating  to  300°. 

This  interpretation  still  fails  to  account  for  the  formation  of  the  de- 
composition products  of  triphenyl-methylamine.  To  account  for  these 
we  would  have  to  assume  that  at  300°  still  another  decomposition  of  the 
hydrazine  occurs,  never  observed  in  its  study,  but  analogous  to  the  well- 
known  decomposition  of  hydrazobenzene  into  aniline  and  azobenzene. 

2(C6H5)3C.NH.NH.C(C6H5)3  ->  2(C6H6)3C.NH2  +  (C6H5)3CN:NC(C6H6)3     (15) 
14  Wieland,  Ber.,  42,  3020  (1909). 


9 

In  that  event,  the  azo  compound  must  be  formed  and  rearrangement 
should  occur  even  in  the  absence  of  air,  which  does  not  seem  to  be  the  case. 
If  we  assume,  therefore,  for  the  present  simply  as  a  working  hypothesis 
that  the  course  of  the  action  is  that  given  in  Scheme  I  and  that  the  forma- 
tion of  phenol  is  actually  due  to  the  oxidation  of  phenyl  groups  escaping 
rearrangement,  then  for  every  molecule  of  triphenyl-methylamine  formed 
there  should  be  produced  either  a  molecule  of  phenylimido-benzophenone 
(Equations  1  and  2)  or  a  molecule  of  phenol.  The  quantity  of  triphenyl- 
methylamine  produced  is  found  by  the  quantitative  determination  of  its 
decomposition  product,  ammonia,  and  the  quantity  of  phenylimido- 
benzophenone  produced  is  found  from  a  volumetric  assay  of  the  aniline 
formed  by  its  hydrolysis.  In  addition,  the  quantity  of  phenol  obtained 
was  also  determined  volumetrically.  Now,  according  to  what  has  been 
developed  above,  the  interpretation  of  the  rearrangement  outlined  under 
I  demands  that  the  sum  of  the  aniline  and  the  phenol  formed  should  be 
roughly  of  the  order15  of  the  amount  of  ammonia  (triphenyl-methylamine) 
obtained.  This  result  is  well  borne  out  by  the  experimental  values  as 
collected  in  Table  II. 

Experimental  Part16 

I.  Preparation  of  syw.-fo's-Triphenylmethymydrazine,  (C6H5)3CNH.- 
NHC(C6H5)3- — For  the  purpose  of  obtaining  better  yields,  the  compound 
was  prepared  by  the  treatment  of  triphenylmethyl  bromide  rather  than 
of  the  corresponding  chloride,17  with  hydrazine  hydrate. 

The  triphenylmethyl  bromide  was  prepared  according  to  the  method  of  Allen  and 
Kolliker18  and  recrystallized  from  benzene.  To  the  hydrazine  hydrate  (8  g.),  covered 
with  absolute  ether  (100  cc.),  the  triphenylmethyl  bromide  (27.4  g.,  95%  pure)  was 
added  in  small  portions  throughout  the  course  of  about  an  hour,  the  mixture  being 
constantly  shaken.  The  reaction  began  immediately  on  the  introduction  of  the  bromide 
and  proceeded  at  ordinary  temperatures  with  evolution  of  heat  and  continuous  precipi- 
tation of  the  s;ym.-fo'5-triphenylmethylhydrazine  and  hydrazine  hydrobromide.  The 
action  was  practically  complete  a  short  time  after  the  last  portion  of  triphenylmethyl 
bromide  was  added,  but  the  reaction  mixture  was  allowed  to  stand  for  a  day  to  insure 
completion.  The  precipitate  was  collected  on  a  filter  and  washed,  in  turn,  with  ether, 

15  Every  molecule  of  triphenyl-methylamine  formed  gives  a  corresponding  mole- 
cule of  ammonia,  our  experiments  having  shown  that  the  ammonia  formation  is  practi- 
cally quantitative  when  triphenyl-methylamine  is  heated  with  zinc  chloride.     But 
some  of  the  phenyl  groups  may  well  escape  combination  with  oxygen  or  with  nitrogen. 
Thus,  the  formation  of  diphenyl  was  strongly  indicated  in  the  last  experiment  under- 
taken.    The  sum  of  the  aniline  and  phenol  formed  should,  therefore,  be  rather  somewhat 
smaller  than  greater,  than  the  amount  of  ammonia  produced. 

16  I  wish  to  use  this  opportunity  to  express  my  appreciation  of  the  skilful   and 
painstaking  manner  in  which  my  young  collaborator,  Mr.  Brown,  has  handled  the 
rather  complex  experimental  material  which  this  problem  has  presented.     All  the  ex- 
perimental work  was  carried  out  by  Mr.  Brown. — J.  S. 

17  Ref.  14,  pp.  3021,  3025.     Ref.  19,  p.  2727. 

18  Allen  and  Kolliker,  Ann.,  227,  110  (1885). 


10 

alcohol,  water,  very  dilute  sodium  hydroxide  solution,  water,  alcohol  and  ether.  The 
yield  was  12.9  g.  of  crude  material  melting  at  213°.  Further  purification  by  the  method 
of  Wieland  gave  11.2  g.  of  the  compound  melting  at  216°.  A  second  recrystallization 
raised  the  melting  point  to  219-220°.  Since  decomposition  takes  place  at  the  melting 
point,  the  melting-point  tube  containing  the  material  was  introduced  into  the  temper- 
ature bath  when  it  was  5°  below  the  melting  point  of  the  compound. 

II.    A  Study  of  the  Decomposition    of    s;yw.-fo's-Triphenylmethyl- 
hydrazine  at  its  Melting  Point 

The  fact  that  the  only  evidences  of  a  rearrangement  had  been  obtained 
when  the  compound  had  been  heated  with  zinc  chloride  at  a  temperature 
higher  than  that  of  its  melting  point,  made  a  study  of  the  melting-point 
decomposition  imperative.  At  its  melting  point  in  air,  fo's-triphenyl- 
methylhydrazine  showed  a  marked  evolution  of  gas  and  gave  as  a  residue 
a  dirty-white  solid  melting  without  purification  at  85°.  This  residual 
solid  mixed  with  triphenylmethane19  melting  at  92°,  gave  a  melting  point 
of  87°-90°.  A  sample  of  1.5  g.  of  the  fo's-triphenylmethylhydrazine  was 
then  heated  at  220-230°  in  an  atmosphere  of  dry  carbon  dioxide  until 
all  evolution  of  gas  ceased  and  the  gas  had  been  swept  into  a  nitrometer 
filled  with  50%  potassium  hydroxide  solution.  The  residual  material, 
while  molten,  was  an  amber  colored  liquid  and  in  the  solid  state  was  a 
yellowish  white  substance. 

The  gas  was  examined  first.  It  showed  no  loss  of  volume  when  passed 
through  a  palladium  black  tube,  such  as  is  used  for  determinations  of  hy- 
drogen by  absorption,  nor  when  passed  into  potassium  hydroxide,  ammoni- 
acal  cuprous  chloride  and  phosphorus  pipets.  This  eliminates  the  possi- 
bility of  hydrogen,  unabsorbed  carbon  dioxide,  carbon  monoxide  and 
oxygen  being  present.  The  gas  was  then  mixed  with  several  volumes 
of  pure  electrolytic  hydrogen,  and  run  into  a  eudiometer  over  mercury 
with  a  little  cone,  sulfuric  acid  on  its  surface.  Continuous  sparking  across 
platinum  electrodes  within  the  tube  produced  a  continuous  reduction  of 
volume  and  the  deposition  of  a  white  solid  on  the  acid-wet  portion  of  the 
inner  walls  of  the  tube.  In  one  experiment  0.7610  g.  of  fo's-triphenyl- 
hydrazine  gave  33.38  cc.  of  gas  (0°,  760  mm.).  The  theoretical  value  for 
the  evolution  of  all  the  nitrogen  as  N2  is  33 . 02  cc.  A  portion  of  the  gas 
(20  cc.)  was  mixed  with  pure  hydrogen  (67  cc.)  and  sparked  until  the  acid 
threatened  to  touch  the  electrodes  within  the  eudiometer.  The  residual 
volume  was  10.2  cc.  or  3.2  cc.  over  the  7  cc.  excess  of  hydrogen  added. 
The  quantity  3 . 2  cc.  is  that  portion  of  the  original  stoichiometric  mixture 
of  80  cc.  (20  cc.  of  N2  +  60  cc.  of  H2)  which  had  not  reacted  to  form  am- 
monia. This  amount  (3.2  cc.)  is  4%  of  the  original  80  cc.  Now,  the 
acid  solution  washed  from  the  eudiometer  and  analyzed  gave  0.0250 
g.  of  ammonia.  Twenty  cc.  of  pure  nitrogen,  measured  under  the  same 

19  Stieglitz  and  Senior,  Ref.  2,  p.  2732. 


11 

conditions  as  prevailed  for  the  20  cc.  of  gas  which  was  mixed  with  hydrogen 
and  sparked,  would  give  0.0261  g.  of  ammonia.  The  ammonia  found 
(0.0250  g.)  is  thus  4.2%  less  than  the  theory  demands,  (0.0261  g.). 
Since  the  gas  unconverted  to  ammonia  is  4%  of  the  original  amount  taken 
and  the  ammonia  found  is  4.2%  less  than  theory  demands  for  this  same 
original  amount  of  nitrogen  and  no  other  gases  were  found,  the  con- 
clusion is  drawn  that  the  gas  from  the  thermal  decomposition  of  the 
hydrazine  was  all  nitrogen. 

The  solid  product  of  the  decomposition  of  foVtriphenylmethylhydrazine 
appeared  in  part  as  a  snow-white  sublimate  and  in  part  as  a  residual  solid 
in  the  bottom  of  the  test-tube.  Samples  of  sublimate  were  needle-like 
crystals  and  melted  at  92°.  When  mixed  with  pure  triphenylmethane19 
melting  at  92°  they  melted  at  92°.  The  identity  of  the  sublimate  is  thus 
established.  The  remainder  of  the  residual  solid  was  crystallized  from  ben- 
zene and  fused  to  free  the  crystals  from  the  molecule  of  benzene  present 
as  benzene  of  crystallization.  The  product  then  melted  at  92°  and  mixed 
with  triphenylmethane  melting  at  92°  gave  a  melting  point  of  91—92°. 
A  sample  of  0  7610  g.  of  fos-triphenylmethylhydrazine  decomposed  under 
the  conditions  previously  stated,  *'.  e.,  in  an  atmosphere  of  carbon  dioxide 
by  heat  in  a  bath  at  220°  to  230°,  gave  0. 6968  g.  of  residue  in  the  test-tube 
and  0.0191  g.  of  sublimate  which  total  0.7159  g.  The  reaction  equa- 
tion calls  for  0.7197  g.  of  triphenylmethane.  Repeated  tests  for  aniline 
and  aniline  derivatives  in  these  residual  solids  were  without  exception 
negative. 

These  results  indicate  that  fo's-triphenylmethylhydrazine  at  its  melting 
point  decomposes  practically  quantitatively  into  nitrogen  and  triphenyl- 
methane. 

HI.    A  Series  of  Attempts  to  Secure  Rearrangement  of  sym.-bis-Tri- 
phenylmethylhydrazine  below  its  Melting  Point  or  in  Solution 

In  view  of  this  decomposition  at  the  melting  point,  an  effort  was  made 
to  secure  rearrangement  in  solution  or  at  temperatures  below  that  at  which 
the  compound  melted.  Although  the  results  were  negative,  the  brief 
description  of  several  may  possibly  save  future  repetition. 

One-half  g.  of  fo's-triphenylmethylhydrazine  was  triturated  with  8  g.  of  anhydrous 
zinc  chloride  and  allowed  to  stand  protected  from  moisture  for  2  months  at  ordinary 
temperature.  The  mixture  darkened  during  this  time,  but  no  trace  of  aniline  could  be 
detected  when  the  mass  was  worked  up  and  tested  according  to  the  method  of  Stieglitz 
and  Senior.19  Analogous  samples  which  had  stood  for  shorter  lengths  of  time  gave  the 
same  negative  results. 

One-half  g.  of  fos-triphenylmethylhydrazine  and  8  cc.  of  dry  benzene  were  heated 
in  a  sealed  tube  at  250°  for  30  minutes.  The  contents  of  the  tube  after  cooling  were 
found  to  be  under  marked  pressure.  The  dark  colored  solution  showed  no  traces  of 
aniline  derivatives  but  contained  nearly  pure  triphenylmethane.  The  pressure  in  the 


12 

tube  was  then  due  to  nitrogen,  the  same  thermal  decomposition  having  taken  place 
as  occurs  when  the  solid  compound  is  heated. 

A  sample  of  the  hydrazine  was  heated  with  finely  ground  dry  zinc  chloride  for  8 
hours  at  100*.  During  this  time  the  yellow  mixture  went  through  a  continuous  color 
change  and  caked  considerably.  Although  no  gas  evolution  was  visible,  the  residual 
hydrocarbons  melted  well  below  100°  indicating  formation  of  triphenylme thane.  No 
aniline  could  be  found  when  the  test  previously  referred  to  was  applied. 

The  fo's-triphenylmethylhydrazine  with  ground  zinc  chloride  was  heated  at  170- 
180°  for  3  hours.  Slight  evolution  of  gas  could  be  detected  and  the  mass  softened.  As 
before,  no  aniline  could  be  detected.  Triphenylmethane  was  identified  as  a  product. 
This  indicates  that  the  thermal  decomposition  of  the  hydrazine  can  be  secured  at  temper- 
atures below  its  melting  point  by  continued  heating. 

A  mixture  of  fo's-triphenylmethylhydrazine  and  zinc  chloride  was  placed  in  dry 
benzene  and  boiled  for  7  hours  under  a  reflux  condenser  at  the  boiling  point  of  benzene. 
The  condenser  had  been  thoroughly  dried  and  was  protected  by  a  calcium  chloride  tube. 
Part  of  the  yellow  color  of  the  mixture  was  taken  up  by  the  benzene.  No  aniline  could 
be  detected  in  the  resulting  solution  or  products.  Triphenylcarbinol  was  identified  as  a 
product.  It  melted  at  158-159°.  Mixed  with  pure  carbinol  (m.  p.  159-160°)  it 
melted  at  158-159°. 

Sw-triphenylmethylhydrazine  (0.065  g.)  was  mixed  with  phosphorus  pentoxide  and 
heated  in  a  test-tube  immersed  in  an  acid  bath  at  105-110°  until  no  further  change  in 
appearance  was  noticeable  (about  2  hours).  No  aniline  or  aniline  derivatives  could  be 
detected  in  the  residue.  A  portion  of  the  original  compound  was  recovered  unchanged. 

A  sample  (0.062  g.)  of  the  hydrazine  was  put  into  water  (50  cc.)  along  with  a 
trace  of  specially  prepared  platinum  black,20  and  held  at  50°  for  30  hours.  The  mix- 
ture was  acidified,  heated,  made  alkaline  and  distilled  with  steam.  No  aniline  could 
be  detected  in  the  distillate.  The  fos-triphenylmethylhydrazine  was  recovered  un- 
changed. 

A  sample  (0.09  g.)  of  the  hydrazine,  approximately  0.04  g.  of  the  platinum  black  and 
water  (20  cc.)  were  heated  in  a  sealed  tube  at  170°  for  1  hour.  Tested  as  above,  no 
aniline  could  be  detected  in  the  contents  of  the  tube.  The  original  compound  was  re- 
covered unchanged. 

Some  of  the  hydrazine  (0.5  g.)  was  heated  with  anhydrous  aluminum  chloride 
(5  g.)  at  180°  for  10  minutes.  The  hydrolyzed  products  gave  no  test  for  aniline.  The 
products  were  not  investigated  further. 

IV.  A  Series  of  Experiments  to  Determine  Conditions  for  a  Maximum 
Rearrangement  by  Zinc  Chloride 

Realizing  that  a  continuance  of  the  experiments  to  effect  the  rear- 
rangement at  temperatures  below  that  of  the  melting  point  of  the  com- 
pound might  result  only  in  a  vain  search  for  a  catalyzer,  we  decided  to 
return  to  the  original  method  of  Stieglitz  and  Senior  and  to  secure  a  greater 
degree  of  rearrangement,  by  a  rigorous  study  of  all  the  conditions  involved, 
than  had  been  obtained  in  this  earlier  work. 

Accordingly,  experiments  were,  carried  out  under  varying  conditions 
and  the  degree  of  rearrangement  was  determined  in  each  case  by  titra- 
tion  of  the  aniline  recovered  with  0. 1  N  sodium  bromate  solution.21  In 

20  Loew,  Ber.,  23,  289  (1891).     Also  see  Tanatar,  Z.  physik.  chem.,  40,  475  (1902) 
and  41,  37  (1902). 

21  Curme.  J.  Am.  Chem.  Soc.,  35.  1162  (1913). 


13 

.articular  the  temperature  and  the  time  of    heating    and    especially, 
the  shape    of    the    vessel    in  which    the    reaction    was    earned 
out 'and    the    time    required    to   heat   the   mixtures   up   to   the    re- 
action temperature  were  varied.     The  results  are  given  in  the  table 
that   follows.     The   significance   of   the   first   8    columns    is    obvious. 
In    the    last    column    is    given    the    result   of   heating  phenylimido- 
benzophenone    under    the    corresponding  conditions  with  zinc  chloride^ 
The   first    !   experiments   (Nos.    12   and  17)  were  carried  out  m  hard 
glass  tubes,  the  next   4   in   an   Erlenmeyer  flask   of   60   cc.   capacity 
on  the  floor  of  which  the  mixture  was  spread  in  a  thin  layer  and  in  the  last 
4  experiments,  for  the  securing  of  still  more  rapid  heating,  a  lOOcc.  Erlen- 
meyer flask  was  used.    A  metol  bath  was  employed  and  the  temperature 
of  the  bath  taken  with  the  aid  of  a  thermocouple.    Since  phenyhmido 
benzophenone,  (C6H5)2C  =  NC6H5,  is  probably  the  actual  product  formed 
by  the  rearrangement  and  the  aniline  is  obtained  by  subsequent  hydrolysis, 
parallel  experiments  under  the  same  conditions  were  made  with  this  pr< 
uct  in  order  to  determine  whether  it  is  destroyed  by  zinc  chloride  under  the 
conditions  of  the  experiment. 

TABLE  I 
DEGREE  OF  REARRANGEMENT  BY  ZINC  CHLORIDE 

Aniline  recovered 
Aniline 


Expt. 

Sample 
G. 

ZnCli 
G. 

Temp. 

Time 
Min. 

Found 
G. 

Calc.° 
G. 

(C«H*)j  =  C  =  N—  C 

12 
17 

0.50 
0.50 

5 
5 

300 
330 

10 

5 

0.005 
0.015 

0.09 
0.09 

6        78.5 
17        90.4 

19 

0.61 

6 

330 

3 

0.024 

0.11 

22          .vl'-: 

21 

0.59 

6  + 

360 

3 

0.032 

0.11 

30 

22 
23 

0.51 
0.52 

6+ 

7 

400 

390+ 

3 

2 

0.030 
0.033 

0.09 
0.09 

33 
37        91.3 

04 

0.55 

7 

390+ 

4 

0.031 

0.10 

31 

^r± 

25 
28 
29 

0.51 
0.78 
0.57 

7 

7 
7 

390  + 
450 
450 

2 
2 

0.028 
0.038 
0.029 

0.09 
0.14 
0.10 

31 
27 
29 

approxi- 
mately 
90 

30 

0.57 

7 

450 

!X/6 

0.035 

0.10 

35 

32 

0.52 

7 

450 

!1/6 

0.031 

0.09 

34 

«  These  values  are  calculated  on  the  basis  of  the  assumption  (Scheme  I,  p.  4 
of  the  introduction)  that  each  molecule  of  hydrazine  yields  one  molecule  of  aniline  i 
not  two  molecules  (as  demanded  by  Scheme  II). 

The  method  used  in  Expts.  30  and  32  was  chosen  as  the  best  under  the 
working  conditions  employed.     Expt.  23  gave  a  better  yield,  but  60cc, 
flasks  of  the  variety  which  after  careful  annealing  would  stand  being 
plunged  repeatedly  into  a  metal  bath  at  the  temperatures  used  were 
then  immediately  available. 

The  method  employed  in  Expts.  30  and  32  was  essentially  this, 
dry  ^5-triphenylmethylhydrazine  was  weighed  into  the  specially  • 


14 

flask,  the  anhydrous  zinc  chloride  finely  ground  in  a  hot  dry  mortar 
added  to  it  and  the  two  were  thoroughly  mixed.  If  the  fo's-triphenyl- 
methylhydrazine  is  pure  and  both  substances  are  thoroughly  dry,  little,  if 
any  yellow  color  appears  when  the  two  are  mixed.  The  flask  was  fitted 
with  an  empty  30cm.  calcium  chloride  tube  and  that  closed  with  a  short 
filled  calcium  chloride  tube.  The  flask  whose  contents,  protected  from 
the  moisture  of  the  atmosphere,  had  thus  been  thoroughly  mixed  and 
shaken  down  into  a  thin  layer  over  the  bottom  of  the  flask,  was  plunged 
into  the  molten  metal  bath  at  450°.  After  70  seconds  it  was  removed 
and  allowed  to  cool.  The  method  for  working  up  the  product  is  essentially 
that  described  below  (p.  18)  for  the  quantitative  examination. 

Examination   and   Identification   of   the   Products   of  Rearrangement 

Aniline. — The  identity  of  this  compound  was  established  by  Senior19 
by  the  analysis  of  its  chloroplatinate.  Besides  the  observation  of  the  char- 
acteristic purple  color  developed  on  the  addition  of  calcium  hypochlorite 
solution  to  the  first  drops  of  the  steam  distillate,  the  tribromo-aniline  ob- 
tained from  the  titration  of  several  of  the  acidified  steam  distillates 
containing  aniline,  was  washed  with  water,  and  recrystallized  from  alcohol. 
This  product  melted  at  118—119°.  When  mixed  with  tribromo-aniline, 
melting  at  119^120°,  it  melted  at  118-120°. 

Phenol. — The  quantitative  preparation  of  phenol  as  tribromo-phenol 
is  described  below  (p.  19).  The  white  precipitates  from  several  titra- 
tions22  were  collected  on  a  filter,  washed  with  water  and  recrystallized 
from  dilute  alcohol.  The  fine,  long,  white  needle  crystals  melted  at  90°. 
Mixed  with  tribromo-phenol,  melting  at  94°,  the  product  melted  at  90-92°. 
The  identity  of  phenol  as  a  product  of  the  reaction  is  thus  established. 

Benzophenone. — The  quantitative  separation  of  benzophenone  in 
the  form  of  its  oxime  is  described  below  (p.  19).  Our  qualitative 
work  by  similar  methods  yielded  a  considerable  quantity  of  almost  pure 
white  crystals  of  benzophenone-oxime  which,  when  dry,  melted  at  137- 
138°.  Mixed  with  benzophenone-oxime  melting  at  141°,  the  substance 
melted  at  138—139°.  This  established  the  presence  of  benzophenone 
among  the  hydrolyzed  rearrangement  products. 

Diphenylene-phenylmethane  and  Triphenylme thane. — The  hydro- 
carbons obtained  (see  below,  p.  20)  melted  at  82-83°.  The  melting 
point  of  this  material19  was  not  raised  by  further  recrystallization  from 
alcohol  or  benzene.  However,  in  concentrated  ether  solution  by  a  careful 
regulation  of  the  rate  of  the  spontaneous  evaporation  of  the  solvent, 
two  distinct  types  of  crystals  were  formed.  One  consisted  of  groups  of 
fine  needles  growing  from  a  common  center;  the  other  was  made  up 
of  a  relatively  small  number  of  large  bar-like  crystals.  Both  were  colorless 

22  See  Koppeschaar,  Z.  anal.   Chem.,  25,   162  (1886). 


15 

and  the  two  were  mechanically  separated  with  ease.  The  first  melted 
at  143-144°  without  purification.  Recrystallization  from  alcohol  gave 
it  a  constant  melting  point  of  145-146°.  Diphenylene-phenylmethane, 
prepared  according  to  Kliegl23  and  freed  from  triphenylmethane,  formed 
at  the  same  time,  and  by  repeated  crystallization  from  alcohol,  melted  at 
145-146°.  An  equal  part  mixture  of  the  two  compounds  of  this  melting 
point  melted  at  145-146°.  This  established  the  identity  of  the  diphenyl- 
ene-phenylmethane  produced  in  our  reaction. 

The  larger  crystals  after  being  pressed  between  two  filter  papers  melted 
at  92  °  without  further  purification.  Mixed  with  triphenylmethane  melting 
at  92°,  they  melted  at  92°  and  hence  were  triphenylmethane. 

Triphenylmethane  and  Gum  Resin. — From  the  resins  left  by  steam 
distillation,  only  triphenylmethane  (m.  p.  91°,  identified  as  usual)  was 
isolated. 

V.    The    Decomposition   of   Triphenyl-methylamine    at   450°    in    the 
Presence  of  Zinc  Chloride  and  the  Establishment  of  the  Existence  of 
Triphenyl-methylamine  as  an  Intermediate  Product  in  the  Rearrange- 
ment of  syw.-fos-Triphenylmethylhydrazine 

Despite  the  thorough  search  made  for  triphenyl-methylamine  and  its 
hydrolytic  product,  triphenylcarbinol,  among  the  rearrangement  products, 
neither  could  be  found.  The  properties  of  triphenyl-methylamine  are 
such  that  quantities  of  it  along  with  some  triphenylcarbinol  should  have 
been  found  without  difficulty,  principally  in  the  gummy  residue  of  the 
steam  distillation  made  in  the  determination  of  the  aniline,  if  it  were 
present  in  the  melt  resulting  from  the  heating  of  fo's-triphenylmethyl- 
hydrazine  with  zinc  chloride  to  effect  the  rearrangement.  Since  none  was 
found  and  its  formation  in  the  rearrangement  was  suggested  by  the  theory 
under  investigation,  its  decomposition  by  zinc  chloride  after  its  formation 
was  indicated.  Hence,  it  became  essential  to  know  the  effect  of  heating 
triphenyl-methylamine  with  zinc  chloride  under  conditions  identical  with 
those  used  to  produce  rearrangement  of  fo's-triphenylmethylhydrazine. 
Accordingly,  triphenyl-methylamine  was  prepared  from  triphenylmethyl 
bromide  and  dry  ammonia.24  To  insure  its  being  free  from  the  hydro- 
bromide,  it  was  extracted  in  a  Soxhlet  apparatus  with  low-boiling  ligroin.25 
It  melted  at  103°  after  crystallization  from  the  ligroin.  The  following 
experiments  were  then  carried  out. 

Triphenyl-methylamine  (1.5  g.)  was  mixed  with  finely  grotmda  nhydrous  zinc  chlo- 
ride (8  g.)  and  heated  at  450°  for  70  seconds,  exactly  as  described  in  the  previous  section 
for  the  rearrangement  of  the  foVtriphenylmethylhydrazine.  The  melt  was  treated  with 

23  Kliegl,  Ber.,  38,  287  (1905). 

24  Elbs,  ibid.,  16,  1276  (1883). 

26  This  method  of  purification  of  triphenyl-methylamine  is  due  to  Mr.  H.  C.  Trimble 
of  this  Laboratory,  whose  dissertation  is,  as  yet,  unpublished. 


16 

ordinary  ether  and  the  resulting  dark  red  solution  was  filtered  from  a  dirty-white  in- 
soluble solid  portion  (A). 

The  solution  was  shaken  with  cone,  sodium  hydroxide  solution,  the  ether  portion 
separated,  dried  with  anhydrous  potassium  carbonate  and  solid  sodium  hydroxide,  and 
evaporated  to  dryness.  The  residue  was  dried  in  vacua  over  solid  potassium  hydroxide. 
It  was  taken  up  in  absolute  ether  and,  because  the  solution  was  not  quite  complete, 
the  ether  extract  was  filtered.  Dry  hydrogen  chloride,  passed  into  the  solution,  gave  a 
flocculent  precipitate  (B).  The  solution  after  filtration  was  partially  decolorized  with 
charcoal  and  evaporated  to  dryness.  The  residual  gum  was  freed  from  ether  in  vacuo 
and  dissolved  in  a  little  benzene.  Crystallization  took  place  rapidly.  A  portion  of  the 
crystals  pressed  between  filter  paper,  fused  on  the  steam-bath  and  allowed  to  solidify, 
melted  at  90-91°.  A  mixture  of  this  with  triphenyl methane  in  equivalent  quantities 
melted  at  91-92°. 

The  insoluble  material26  (A)  when  covered  with  a  little  cone,  sodium  hydroxide 
solution  and  warmed  gave  copious  quantities  of  ammonia.  It  evidently  consisted  of  a 
zinc  ammonium  chloride. 

The  precipitate  (B)  was  a  clay  colored,  slimy  material,  which  caked  on  the  filter 
paper  as  it  dried.  It  was  very  slightly  soluble  in  alcohol  and  insoluble  in  water,  in  ether 
and  in  ligroin.  It  dissolved  in  chloroform  and  benzene,  but  crystallized  from  neither. 
On  evaporation  of  these  solvents  both  spontaneously  and  by  heat  no  crystals  could  be 
obtained  and  the  residue  was  a  resin.  When  precipitated  from  either  of  these  solvents 
by  the  addition  of  low-boiling  ligroin,  the  substance  was  a  clay  colored,  amorphous  mate- 
rial. Examination  under  the  microscope  showed  no  crystalline  material.  It  gave 
no  test  for  chlorine  or  the  chloride  ion.  Repeated  treatment  with  cone,  ammonium 
hydroxide  produced  no  change  in  its  properties.  It  possessed  no  melting  point  but 
darkened  and  shrank  into  a  hard  resin  above  220°.  Even  at  290°  no  fusion  had  taken 
place.  This  cannot  be  the  hydrochloride  of  unchanged  triphenyl-methylamine. 

In  a  further  experiment  the  melts  from  two  more  samples  of  the  fusion  of  triphenyl- 
methylamine  with  zinc  chloride  were  washed  into  separate  flasks,  treated  with  alkali  and 
distilled  for  ammonia  in  the  usual  way. 

Analyses.  Subs.,  (1)  0.5805,  (2)  0.5402.  Calc.  for  triphenyl-methylamine: 
NH3,  0.0381,27  0.0355.  Found:  0.0366,  0.0345. 

The  melt  from  a  third  sample  was  dissolved  in  ether  and  dil.  hydrochloric  acid. 
Each  of  the  two  solutions,  after  being  well  shaken  and  separated,  was  washed  thoroughly 
with  the  other  solvent.  The  portions  of  like  solvents  were  combined.  The  aqueous 
portion  containing  the  zinc  chloride  and  the  ammonia  was  rendered  strongly  alkaline 
and  distilled  for  ammonia. 

Analysis.  Subs.,  (3)  0.5916.  Calc. :  NH3,  0.0388.  Found:  0.0384. 
This  result,  in  view  of  the  separation  of  the  ether  and  aqueous  portions  before  dis- 
tillation and  the  fact  that  no  triphenylcarbinol  was  obtained  from  the  distillation  residue 
in  (1)  and  (2),  eliminates  the  possibility  of  any  hydrolysis  of  unchanged  triphenyl- 
methylamine  in  the  first  two  determinations.  Hence,  we  conclude  that  triphenyl- 
methylamine,  when  heated  under  the  conditions  previously  stated,  gives  up  its  nitrogen 
as  ammonia  practically  quantitatively. 

In  the  distillate  of  Determinations  1  and  2  were  small  quantities  of  solid  hydro- 
carbons which,  on  crystallization  from  the  ether  with  which  they  were  extracted,  melted 
at  143-144°.  Recrystallized  from  alcohol  and  mixed  with  diphenylene-phenylmethane 

26  The  exact  nature  of  this  zinc  chloride  ammonia  complex  was  not  investigated. 

27  This  value  was  calculated  on  the  basis  of  one  molecule  of  NH8  for  one  molecule 
of  triphenyl-methylamine. 


17 

melting  at  145°,  it  gave  a  melting  point  of  142-143  °.  Diphenylene-phenylmethane  is 
thus  identified  as  one  of  the  products  of  decomposition. 

As  in  the  other  experiment  the  residue  from  the  ammonia  Distillations  1  and  2  and 
the  ether  solution  of  3  yielded  triphenylmethane  and  gum  or  resin. 

A  sample  of  triphenyl-methylamine  heated  alone  at  450°,  as  before,  gave  a  strong 
odor  of  ammonia  and  a  residue  of  triphenylmethane,  diphenylene-phenylmethane  and 
resin.  This  decomposition  is  entirely  analogous  to  the  thermal  decomposition  of  tri- 
phenylmethyl  bromide  and  triphenylmethyl  chloride  in  which,  respectively,  hydrogen 
bromide  and  hydrogen  chloride  together  with  triphenylmethane,  diphenylene-phenyl- 
methane and  resin  are  obtained  ;28  and  the  decomposition  with  zinc  chloride  present  is  not 
unlike  the  decomposition  of  triphenylcarbinol  when  heated  with  solid  phosphoric  acid,21 
except  that,  in  the  latter  case,  water  is  removed  instead  of  ammonia,  the  quantity  of 
diphenylene-phenylmethane  formed  is  much  greater  and  the  quantity  of  resin  is  very 
small. 

In  a  further  experiment  a  sample  of  triphenyl-methylamine  (0.294  g.)  with  zinc 
chloride  (8  g.)  was  heated  as  before  at  450°  for  70  seconds.  The  melt  was  dissolved 
in  ether  and  hydrochloric  acid,  and  the  ether  portion  was  separated  and  shaken  with 
20  cc.  of  2  N  sodium  hydroxide  solution.  The  alkali  extract  was  rendered  acid  and 
distilled  with  steam.  The  first  portion  (1  cc.)  was  divided  into  three  parts  and  tested 
for  phenol  as  follows:  (1)  by  the  addition  of  ferric  chloride;  (2)  by  the  addition  of 
Millon's  reagent  and  then  nitric  acid;29  (3)  by  boiling  with  dil.  nitric  acid  which  will  re- 
veal traces  of  phenol  by  the  odor  of  0-nitrol-phenol  in  the  hot  solution.  All  tests  failed 
to  detect  any  phenol.  A  parallel  experiment  with  phenylimido-benzophenone  (0.220  g.) 
yielded  negative  results  in  all  three  tests. 

All  the  decomposition  products  of  triphenyl-methylamine  had  been  recovered  from 
the  melt  of  tas-triphenylmethylhydrazine  and  identified  as  such  except  ammonia. 
.Bw-triphenylmethylhydrazine  (0.901  g.)  and  finely  ground  dry  zinc  chloride  (10  to  11  g.) 
were  therefore  heated  under  the  conditions  and  hi  the  manner  previously  described  for 
this  compound.  The  melt  was  treated  with  ether  and  a  small  quantity  of  water.  The 
aqueous  portion  when  made  strongly  alkaline  with  concentrated  sodium  hydroxide  and 
warmed,  gave  a  strong  odor  of  ammonia.  The  gaseous  ammonia  turned  moistened  red 
litmus  paper  blue  and  gave  a  heavy  brown  precipitate  with  Nessler's  reagent. 

Another  sample  of  fo's-triphenylmethylhydrazine  (0.5  g.),  without  being  mixed 
with  zinc  chloride,  heated  at  450°  gave  no  detectable  ammonia,  neither  was  any  ani- 
line to  be  detected  in  the  hydrolyzed  products;  while  a  sample  (0.2295  g.)  of  phenyl- 
imido-benzophenone30 heated  in  the  same  way  gave  83%  of  the  theoretical  amount 
of  aniline.  The  ether  solution  of  the  hydrocarbons  from  this  heating  of  fos-triphenyl- 
methylhydrazine,  after  decolorization  with  a  little  charcoal,  yielded  only  triphenyl- 
methane on  complete  evaporation.  This  melted  at  90-91°.  Apparently  fos-triphenyl- 
methylhydrazine  does  not  rearrange  when  it  is  heated  in  the  absence  of  zinc  chloride, 
and  ammonia  is  not  produced  when  the  rearrangement  does  not  take  place. 

28  Elbs,  Ber.,  17,  701  (1884).  Hemilian,  ibid.,  7,  1208  (1874);  ibid.,  11,  837  (1878). 
E.  and  O.  Fischer  ibid.t  11,  613  (1878);  Ann.,  194,  257  (1878).  Nef.,  ibid.,  309,  167 
(1899).  Schwarz,  Ber.,  14,  1522  (1881). 

^Almen,  Jahresber.,  1878,  1079. 

30  This  product  was  prepared  by  the  reaction  of  Reddelieu,  Ber.,  42,  4760  (1909), 
but  purified  as  follows.  At  the  end  of  the  reaction,  the  melt  was  shaken  with  strong 
alkali,  separated  and  distilled  in  vacua  to  remove  the  excess  of  aniline.  The  well-cooled 
residue  was  freed  from  the  remainder  of  the  aniline  on  a  cold  porous  plate  and  twice 
recrystallized  from  dil.  alcohol.  The  product  formed  beautiful  yellow  flaky  crystals, 
analyzing  on  hydrolysis  for  the  calculated  amount  of  aniline. 


18 

There  can  be  little  question  but  that  triphenyl-methylamine  was  a 
primary  product  of  the  rearrangement  and  subsequently  underwent  the 
characteristic  decomposition  of  that  compound  as  outlined  in  the  pre- 
ceding paragraphs.  This  is  established  by  the  following  facts  holding 
for  the  conditions  of  the  rearrangement  of  fo's-triphenylmethylhydrazine : 
(1)  triphenyl-methylamine  gave  practically  a  quantitative  yield  of  am- 
monia; (2)  benzophenone-phenylimide  does  not  yield  ammonia;  (3) 
triphenyl-methylamine  gave  no  hydrocarbon  products  not  found  among 
those  of  foVtriphenylmethylhydrazine ;  (4)  fo's-triphenylmethylhydrazine 
did  not  give  ammonia  when  it  did  not  undergo  rearrangement  and  did 
give  it  when  it  did  rearrange;  (5)  the  molecular  nitrogen  and  the  tri- 
phenylmethane  from  the  portion  that  underwent  thermal  decomposition 
and  the  phenol  present  could  not  give  ammonia.  Further  evidence  bear- 
ing out  this  conclusion  is  to  be  found  in  the  quantitative  study  of  the  re- 
arrangement products. 

VI.    The  Quantitative  Study  of  the  Rearrangement  Products  of  sym.- 
fo's-Triphenylmethylhydrazine 

For  a  quantitative  study  of  this  rearrangement,  approximately  15  g. 
of  fo's-triphenylmethylhydrazine  was  worked  up  in  small  portions.  For 
the  best  yield  of  aniline  under  the  conditions  employed  portions  of  about 
half  a  gram  should  have  been  used.  Individual  yields  in  this  series  (Table 
II)  were  sacrificed  somewhat  for  total  quantity  of  material  worked  up. 
Expts.  39  to  47  represent  single  samples,  while  in  Expts.  47  to  51  two 
samples  were  heated  separately  and  then  combined  for  analysis  in  each 
experiment.  The  ratio  of  the  hydrazine  to  zinc  chloride  was  about  1 :10. 
The  preparation  and  heating  of  samples  were  as  given  in  detail  in  the  pre- 
vious series  of  rearrangements. 

After  cooling  the  melt,  it  was  treated  with  ordinary  ether  and  a  little  dil.  hydro- 
chloric acid  which  took  most  of  it  into  solution.  The  mixture  was  heated  for  several 
minutes  under  a  reflux  condenser  to  hydrolyze  the  phenylimido-benzophenone;31  it  was 
shaken  thoroughly  and,  finally,  the  two  solutions  were  separated  carefully.  The 
aqueous  portion  was  extracted  thrice  with  ether.  Each  of  these  ether  extracts  was  washed 
with  dil.  acid.  The  original  ether  solution  was  washed  twice  with  dil.  acid.  The  acid 
portions  were  combined  and  likewise  the  ether  portions  and  the  combined  portions 
filtered.  This  gave  three  products,  (a)  the  acid  portion,  (b)  the  ether  portion,  and  (c) 
the  insoluble  portion. 

The  acid  portion  (a)  containing  the  ammonia,  zinc  chloride  and  the  aniline  formed 
by  the  hydrolyzed  phenylimido-benzophenone  was  made  strongly  alkaline  in  a  closed 
apparatus  and  distilled  with  steam  into  20  cc.  of  6  N  sulfuric  acid.  The  distillate  (400 
cc.)  was  extracted  with  alcohol-free  ether  to  remove  any  hydrocarbons,32  freed  from  any 

31  The  completeness  of  this  hydrolysis  was  tested  in  this  way:  0.2297  g.  of  phenyl- 
imido-benzophenone was  treated  as  indicated  in  the  text  and  the  aqueous  portion  ti- 
trated for  aniline.     Calc.  for  aniline:    0.0831  g.     Found:    0.0828  g. 

32  Despite  the  complete  hydrolysis  of  the  phenylimido-benzophenone  and  the  thor- 


19 

dissolved  ether  and  titrated  for  aniline  with  standard  bromate  solution.  A  slight  excess 
of  sodium  thiosulfate  was  added  and  the  tribromo-aniline  removed  by  filtration.  The 
filtrate  was  then  made  alkaline  and  the  ammonia  distilled  in  the  usual  manner.  Cochi- 
neal was  used  as  the  indicator  33 

The  ethereal  portion  (b),  containing  the  phenol,  all  the  hydrocarbons  and  benzo- 
phenone,  was  shaken  with  sodium  hydroxide  solution  (15  to  20  cc.  of  2  N)  and  two  like 
portions  of  water.  The  combined  aqueous  portions  containing  all  the  phenol34  were  rid 
of  dissolved  ether,  made  acid  with  hydrochloric  acid  and  distilled  with  steam  into  dil. 
sodium  hydroxide  (5  cc.).  The  distillate  (300  cc.)  was  rendered  strongly  acid  and  ti- 
trated with  standard  bromate  solution  for  phenol. 

The  ethereal  solution  of  hydrocarbons  and  benzophenone  from  the  whole  series  or 
rearrangements  was  distilled  nearly  to  dryness  and  distilled  with  steam  until  the  dis- 
tillate had  entirely  ceased  to  be  milky  in  appearance.  Solid  hydrocarbons  were  still 
coming  over  but  the  benzophenone  was  practically  all  distilled.35 

The  recovery  of  benzophenone  from  the  hydrocarbon  mixture,  extracted  from  the 
steam  distillate,  was  carried  out  essentially  as  described  earlier  in  this  paper.  The 
mother-liquor,  after  the  removal  of  the  benzophenone-oxime,  was  extracted  and  this 
extract,  together  with  the  mixture  of  hydrocarbons  previously  removed,  was  treated 
a  second  time  for  benzophenone.  A  very  small  second  crop  of  the  oxime  was  obtained. 

The  mixture  of  triphenylmethane  and  diphenylene-phenylmethane  precipitated 
from  the  alkaline  solution  of  benzophenone-oxime,  after  being  washed  free  from  alkali, 
melted  at  80-84°.  This  was  dissolved  in  a  little  ether  and  by  a  careful  control  of 
the  concentration,  two  crops  (1.10  g.)  of  tripheny  hue  thane,  m.  p.  90°,  were  removed. 
The  diphenylene-phenylmethane  (0.05  g.)  was  then  crystallized,  and  recrystallized  from 
alcohol.  It  melted  at  145-146°. 

The  residue  from  the  distillation  with  steam  was  extracted  with  ether  and  the  ex- 
tract treated  with  animal  charcoal,  filtered,  dried  with  calcium  chloride,  distilled  to 
dryness  and  freed  from  ether  in  vacua.  Benzene  was  added  to  this  residual  gum  and 

ough  extraction  of  the  acid  portion  (a)  with  ether,  there  was  some  neutral  product 
distilled  at  this  point.  This  proved  to  be  benzophenone  melting  at  45°.  It 
was  added  to  the  ethereal  portion  (b).  This  suggests  the  probability  of  formation 
of  a  complex  oxonium  salt  of  benzophenone.  The  quantity  of  this  material  va- 
ried greatly.  The  controlling  factors  were  not  investigated  but  will  be  determined 
in  this  Laboratory.  See  Maass  and  Mclntosh,  /.  Am.  Chem.  Soc.  33,  71  (1911). 

33  The  presence  of  the  ammonium  salt  in  no  way  affected  the  aniline  titration. 
(See  Kingscott  and  Knight,  "Quantitative  Organic  Analyses,"  Longmans,  Green  and 
Co.,  1914,  p.  257;   Sutton,  "Volumetric  Analyses,"  Blakiston's  Son  and  Co.,  1911,  p. 
387).      The    accuracy    of    the    ammonia    determination    from    the    filtrate  was  suf- 
cient  for  the  purpose  for  which  it  was  used.     Some  blank  experiments   gave   these 
results:   0.0345   g.   of  aniline   and   0.1164   g.  of  ammonium  sulfate  (NH3  content, 
0.0300   g.)    gave   0.0344  g.  of  aniline  and  0.0303  g.  of  NH3;   0.0345  g.  of  aniline 
and  0.1164  g.  of  ammonium  sulfate  gave  0.0344  g.  of  aniline  and  0.0301  g.  of  NH3. 

34  The  completeness  of  the  separation,  and  the  absence  of  condensation,  of  the 
aniline  and  the  phenol  on  being  heated  with  a  concentrated  solution  of  zinc  chloride 
and  hydrogen  chloride  were  tested.     A  typical  experiment  gave  these  results:    0.0345 
g.  of  aniline,  0.0305  g.  of  phenol  and  0.0887  g.  of  ammonium  sulfate   (NHS  content 
0.0229  g.)  gave  0.0346  g.  of  aniline,  0.0304  g.  of  phenol  and  0.0232  g.  of  ammonia. 

35  Benzophenone  (0.70  g.)  was  distilled  with  steam,  the  condenser  terminating  in 
an  adapter  which  dipped  beneath  the  surface  of  the  distillate  as  in  the  aniline,  ammonia 
and  phenol  distillations.     From  the  first  400  cc.  of  the  distillate  0.672  g.  of  benzo- 
phenone was  recovered  by  extraction. 


20 

from  it  two  crops  of  triphenylmethane  crystals,  totaling  3.3  g.,  were  obtained.  The 
gum  after  removal  of  the  crystals  was  again  subjected  to  distillation  with  steam  until 
800  cc.  of  distillate  had  accumulated.  This  distillate  on  extraction  yielded  0.2  g.  of 
hydrocarbons,  which  were  very  largely  diphenylene-phenylmethane  (m.  p.  144°). 
The  small  amount  of  contaminating  material  proved  to  be  triphenylmethane.  The 
residue  from  distillation  with  steam  (a)  was  again  extracted,  dried  in  vacua  and  treated 
with  benzene  in  an  effort  to  obtain  further  crystallization.  The  crystals  formed  were 
extremely  small  in  amount  and  were  not  recovered. 

The  insoluble  residue  (c)  left  after  treatment  of  the  melt  with  ether  and  aqueous 
acid,  was  subjected,  in  the  original  filter  papers,  to  extraction  in  a  modified  Soxhlet 
apparatus  with  chloroform  as  the  solvent.  This  gave  a  carbonized  residue  (/3)  and  a 
chloroform  solution  of  a  resin-like  material  (7)  in  no  way  distinguishable  from  the 
precipitate  (B)  described  in  connection  with  the  decomposition  of  triphenyl-methyl- 
amine, except  that  it  was  darker  in  color.  This  will  be  discussed  later. 

A  portion  (1.12  g.)  of  the  benzophenone-oxime  recovered  was  dissolved  in  alcohol, 
dil.  hydrochloric  acid  added  and  the  solution  boiled  for  several  hours;  it  was  then  diluted 
and  extracted  with  ether.  The  dried  extract  yielded  an  oil  which  crystallized  on  being 
seeded  with  a  crystal  of  benzophenone.  This  weighed  1.02  g.  and  melted  at  45°. 
Recrystallized  from  ligroin  it  melted  at  47.5°  to  48°. 

The  identification  of  each  of  the  compounds  obtained  was  carried  through  again  as 
follows. 


MELTING   POINTS 


Compound 


Known 
Found  compound  Mixed  sample 


Ammonia 

Tribromo-aniline 118-119  '  119-120            118-120 

Tribromophenol 91-92  92-93                92-93 

Benzophenone 

as  oxime 139 .5  141                    140-141 

as  benzophenone 47.5-48  48                      47 

Triphenylmethane 

(from  the  steam  distillate)...  90  92                      90-91 

(from  the  steam  distillation 

residue) 90-91  92                       90-91 

Diphenylene-phenylmethane 145-146  145-146             145-146 

The  gum  or  resin  (a)  residue  from  the  distillation  with  steam  and  removal  of  tri- 
phenylmethane was  apparently  identical  with  that  obtained  in  the  decomposition  of 
triphenyl-methylamine  and  as  such  was  considered  as  a  final  product. 

The  residue  (/3)  from  the  chloroform  extraction  of  insoluble  portion  (c)  from  the 
original  melt  was  in  no  way  distinguishable  from  carbon  in  its  behavior  in  a  flame  and  its 
total  insolubility  in  benzene,  a  characteristic  of  free  carbon. 

As  previously  stated  the  residue  (7)  after  evaporation  of  the  chloroform  was  iden- 
tical in  every  way  but  depth  of  color  with  the  material  obtained  from  the  decomposition 
of  triphenyl-methylamine.  It  showed  the  same  solubilities  and  when  precipitated  from 
chloroform  with  low-boiling  ligroin  and  dried,  it  gave  the  caked  smear.  Repeated  pre- 
cipitation failed  to  purify  or  change  it.  When  heated  in  a  melting-point  tube,  it  dark- 
ened and  shrank  from  225-230°  up  (heated  to  290°)  but  never  melted  so  as  to  spread  on 
or  stick  to  the  tube.  After  the  heating,  the  material  was  shaken  out  of  the  tube  and 
formed  a  hard,  dark  resin.  It  was  probably  a  highly  condensed  or  polymerized  mass. 
A  sample  of  the  precipitated  material  finely  ground  was  treated  in  aqueous  suspension 


21 

with  concentrated  ammonium  hydroxide.  It  underwent  no  change  in  appearance  or  the 
properties  evidenced  under  heat  and  solvent.  Treatment  with  other  alkalies  and  acids 
did  not  affect  it.  These  properties  are  not  unlike  those  exhibited  by  the  very  highly 
polymerized  products  of  the  indene  and  cumarone  series  and  other  partly  unsaturated 
bodies. 

The  quantitative  determinations  of  the  rearrangement  products  of  this 
series  are  given  in  the  table  that  follows.  In  this  table,  Part  1  gives  the 
results  for  aniline,  phenol  and  ammonia:  Col.  1  gives  the  number  of  the 
experiment,  Col.  2  the  weight  of  samples  used  (given  in  values  rounded  to 
centigrams  but  calculated  to  milligrams),  Col.  3  the  aniline  found,  Col.  4 
the  yield  of  aniline  expressed  in  percentages  of  the  maximum  calculated 
yield.  In  Col.  5  the  weight  of  phenol  is  given  and  in  Col.  6  the  equivalent 
percentage  of  aniline,  calculated  on  the  assumption  that  each  molecule 
of  phenol  represents  a  molecule  of  aniline  lost  in  the  rearrangement  (see 
the  introduction).  In  Col.  7  we  have  the  sum  of  the  aniline  actually  found 
and  of  the  aniline  equivalent  of  the  phenol  found.  In  Col.  8  the  amount 
of  ammonia  found  is  given  and  in  Col.  9  the  percentage  of  the  calculated 
yield  found,  figured  on  the  basis  of  the  assumption  that  each  molecule 
of  hydrazine  gives  by  way  of  triphenyl-methylamine  a  molecule  of  am- 
monia. In  Part  2,  the  results  for  benzophenone  are  summarized,  the 
calculations  being  based  on  the  23.94%  of  rearranged  substance  shown 
by  the  aniline  of  the  total  of  Col.  4  of  the  first  part  of  the  table.  In  Part 
3  the  yields  of  other  products  are  given  in  grams. 

TABLE  II 
QUANTITATIVE  DETERMINATION  OF  THE  REARRANGEMENT  PRODUCTS 

1.  Aniline,  Ammonia  and  Phenol 
1  234  56789 


No. 

Sample 

Aniline  found 
%of 

Phenol 
found 

An.  eq. 

Sum  of 
aniline 
and 
an.  eq. 

Ammonia 

found 

G. 

G. 

Calc. 

G. 

% 

% 

G. 

% 

39 

0.77 

0.040 

28.8 

0.035 

25.1 

53.9 

0.016 

64.0 

40 

0.77 

0.043 

31.0 

0.030 

21.6 

52.6 

0.014 

56.0 

41 

0.65 

0.026 

22.2 

0.032 

27.4 

49.6 

0.013 

61.9 

42 

0..76 

0.028 

20.4 

0.038 

27.8 

48.2 

0.016 

64.0 

43 

1*02 

0.046 

25.0 

0.037 

20.5 

45.5 

0.021 

61.8 

44 

1.35 

0.053 

21.8 

0.067 

27.3 

49.1 

0.031 

69.0 

45 

1.54 

0.038 

13.7 

0.048 

17.3 

31.0 

0.026 

51.0 

46 

0.52 

0.027 

28.7 

0.029 

30.9 

59.7 

0.0115 

67.6 

47 

1.61 

0.071 

24.5 

0.067 

22.7 

47.2 

0.0321 

60.4 

48 

1.46 

0.069 

26.2 

0.074 

28.2 

54.4 

0.033 

68.7 

49 

1.61 

0.072 

24.8 

0.074 

25.2 

50.0 

0.031 

58.5 

50 

1.50 

0.068 

25.2 

0.075 

27.4 

52.6 

0.033 

67.3 

51 

1.55 

0.071 

25.5 

0.080 

28.3 

53.8 

0.033 

64.7 

Total 

15.11 

0.652 

23.94 

6.686 

24.94 

48.9 

0.3105 

62.3 

22 
2.  Benzophenone 

Sample  Benzophenone-oxime  Benzophenone 

taken  Found  Calc.  Found  Calc. 

15.12  1.2236  1.38  1.12  1.27 

3.  Other    Products 

From  steam  From  steam 

distillate  distillate  residue                Total 

G.  G.                             G. 

Triphenylmethane 1 . 10  3 .30  4 .40 

Diphenylene-phenylmethane .25  .  .  0 .25 

Gum  resin-steam  dist.  residue. .  .  6 .35  6 .35 

Carbonized  residue  (0) .  .  0 .30 

Resinous  material  (7) . .  . .  0 .35 

VII.    Rearrangements  of  syw.-fo's-Triphenylmethylhydrazine  in  Other 

Atmospheres  than  Air37 

With  a  view  to  the  study  of  the  rearrangement  and  the  coincidental 
thermal  decomposition  by  accounting  for  the  whole  of  the  nitrogen  of  the 
molecule  in  the  products  found,  attempts  were  made  to  secure  the  re- 
arrangement of  the  hydrazine  in  an  atmosphere  of  carbon  dioxide.  It 
was  expected  that  possibly  a  relation  could  be  found  between  the  per- 
centage of  the  fo's-triphenylmethylhydrazine  that  underwent  the  primary 
decomposition  into  nitrogen  and  triphenylmethane  and  the  percentage 
of  the  fo's-triphenylmethylhydrazine  which  underwent  the  rearrangement, 
and  that  by  the  measurement  of  the  nitrogen  evolved  and  the  aniline 
produced  at  various  temperatures,  the  extent  of  the  thermal  decompo- 
sition and  of  the  rearrangement  would  be  given.  It  was  proposed  to  begin 
at  temperatures  below  300°,  this  being  the  only  temperature  at  which, 
at  that  time,  the  arrangement  had  been  effected.38  Accordingly,  the 
following  experiments  were  carried  out. 

A  sample  (0.514  g.)  of  Ws-triphenylmethylhydrazine  was  weighed  into  a  hard  glass 
tube,  5  g.  of  finely  ground  anhydrous  zinc  chloride  added  and  the  two  intimately  mixed. 
The  tube  was  connected  with  a  source  of  dry  carbon  dioxide  and  by  an  outlet  to  a  nitrom- 
eter. When  the  apparatus  had  been  freed  from  air,  the  tube  was  immersed  in  an  oil- 
bath  at  275°  and  retained  there  until  nitrogen  had  ceased  to  be  evolved.  The  nitrogen 
collected  amounted  to  3.7  cc.  at  23°  and  738.1  mm.,  uncorrected.  The  melt  was  dis- 
solved out  with  ether  and  water,  washed  well  with  cone,  sodium  hydroxide  solution, 

36  One  g.  of  benzophenone  and  2.3  g.  of  triphenylmethane  yielded  0 . 95  g.  of  benzo- 
phenone-oxime  and  2.27  g.  of  triphenylmethane  when  the  mixture  was  treated  as  out- 
lined in  the  text  of  this  paper.  Calc.,  1.08  g.  of  the  oxime.  Hence  1.22  +  0.13  = 
1 .35  g.  of  the  oxime  calculated  (1 .38)  in  the  text  is  accounted  for. 

?7  This  work  was  done  before  the  decomposition  of  triphenyl-methylamine  was  in- 
vestigated and  the  presence  of  ammonia  among  there  arrangement-decomposition  prod- 
ucts of  fo's-triphenylmethylhydrazine  was  discovered  and  its  quantity  taken  as  the 
measure  of  the  minimum  portion  of  the  fo's-triphenylmethylhydrazine  which  originally 
split  into  triphenyl-methylamine  and  the  univalent  nitrogen  derivative,  which  re- 
arranges to  give  phenylimido-benzophenone  and  phenol. 

38  By  ourselves  and  by  Stieglitz  and  Senior,  Ref.  19,  p.  2731. 


23 

hydrolyzed  and  distilled  with  steam  after  the  addition  of  sodium  hydroxide.  No  aniline 
could  be  detected  in  any  portion  of  the  distillate  with  calcium  hypochlorite  solution. 
The  solid  hydrocarbons  in  the  distillate  softened  from  70°  up  and  melted  at  78-84°. 
Beyond  this  they  were  not  investigated  at  this  time. 

A  sample  (0.664  g.)  of  fo's-triphenylmethylhydrazine  was  treated  as  above  except 
that  a  temperature  of  300°  was  used.  The  evolution  of  the  nitrogen  seemed  to  be 
complete  in  about  3  minutes  and  it  had  all  been  swept  over  at  the  end  of  10  minutes. 
The  gas  collected  amounted  to  6.8  cc.,  at  24°  and  752.5  mm.,  unconnected.  As  before, 
all  efforts  to  detect  aniline  among  the  hydrolyzed  products  failed.  The  hydrocar- 
bons extracted  from  the  distillate  with  steam  melted  at  78-81  °  and,  mixed  with  an 
equal  quantity  of  triphenylmethane  melting  at  92°.  melted  at  85-88°.  They  were 
not  further  investigated. 

After  the  rearrangement  in  air  had  been  developed  to  give  a  yield  of  35%  of  the 
calculated  amount,  the  conditions  of  temperature,  time,  and  container  and  methods  of 
manipulation  were  applied  to  secure  rearrangement  in  carbon  dioxide.  Four  experi- 
ments were  made.  A  mixture  of  0.518  g.  of  fa's-triphenylmethylhydrazine  and  7  g.  of 
zinc  chloride  prepared  as  described  earlier  in  this  paper  was  heated  in  an  atmosphere  of 
carbon  dioxide,  prepared  by  the  heating  of  pure  sodium  hydrogen  carbonate,  and  dried 
by  being  passed  through  2  sulfuric  acid  wash-bottles.  After  the  flask  had  cooled  it  was 
immersed  in  an  ice-bath  and  the  nitrogen  swept  into  the  nitrometer.  The  melt  was 
lighter  in  color  than  those  produced  in  air,  being  brown,  and  had  no  odor  of  phenol  but 
one  resembling  that  of  diphenyl.  It  was  dissolved  in  ether  and  water;  the  resulting 
solutions  were  shaken  with  cone,  sodium  hydroxide  solution  and  the  ethereal  solution  sep- 
arated. To  this  ethereal  extract,  aqueous  and  ethereal  solutions  of  hydrogen  chloride 
were  added,  and  the  ether  was  distilled.  The  residue  was  warmed  for  20  to  30  min- 
utes on  the  water-bath,  made  alkaline  and  distilled  with  steam.  No  trace  of  aniline  was 
found  in  the  distillate.  The  hypochlorite  test  as  applied  easily  detected  0.01  mg.  of 
aniline  in  the  same  volume  of  solution. 

The  above  experiment  was  repeated  with  0.556  g.  of  fos-triphenylmethylhydrazine. 
Fifty  cm.  of  tubing  filled  with  glass  beads  covered  with  phosphorus  pentoxide  had  been 
added  to  the  drying  system.  The  first  few  drops  of  the  distillate  gave  a  very  faint 
coloration  with  the  hypochlorite  solution.  The  test  was  considered  exceedingly  doubtfuf. 

The  experiment  was  again  repeated  with  0.616  g.  of  fos-triphenylmethylhydrazine, 
the  carbon  dioxide  being  generated  from  pure  magnesite.  The  first  portion  (1  cc.)  of 
distillate  in  this  case  gave  an  appreciable  color  with  hypochlorite  solution.  The  color 
was  not  quite  the  characteristic  purple  but  may  have  been  affected  by  the  opalescence  of 
the  distillate  due  to  the  hydrocarbons  present. 

One  more  experiment  was  made  with  0.501  g.  of  the  fas-triphenylmethylhydrazine. 
As  in  the  last  experiment,  the  first  portion  (1  cc.)  of  the  distillate  with  steam  gave  a 
coloration  with  the  hypochlorite  solution. 

In  each  of  these  experiments  the  first  400  cc.  of  the  acid  distillate  with  steam  was 
extracted,  freed  from  dissolved  ether  and  titrated  with  standard  bromate  solution. 
Some  bromate  solution  was  used  up  and  varied  in  amounts  equivalent  to  2  to  5  mg.  of 
aniline.  In  no  case,  however,  was  there  a  precipitate  of  tribromo-aniline,  while  3  mg.  of 
aniline  gives  a  marked  precipitate  of  tribromo-aniline.  Further,  after  extraction  of  the 
distillate  in  the  fifth  experiment,  it  was  diluted  to  exactly  500  cc.  and  divided  into  two 
250  cc.  portions.  One  portion  was  rid  of  dissolved  ether  and  then  titrated  with  standard 
bromate  solution.  It  required  0.71  cc.  of  the  solution.  The  second  portion  (250  cc.) 
was  made  alkaline,  extracted,  freed  from  ether,  acidified  and  titrated.  This  portion  re- 
quired 0.72  cc.  of  the  bromate  solution.  The  extract  of  the  second  portion,  on  being 
evaporated  in  a  very  slow  stream  of  dry  air,  yielded  no  residue.  The  distillate  of  Expt. 
4  was  extracted  10  times  with  a  total  of  500  cc.  of  ether  free  from  alcohol,  and  required 


24 

approximately  the  same  quantity  of  bromate  solution  as  the  other  distillates.  After 
the  standard  solutions  used  in  these  titrations  had  been  checked,  and  0.0070  g.  of  aniline 
out  of  the  0.0101  g.  theoretically  possible  had  been  recovered  from  0.0279  g.  of  phenyl- 
imido-benzophenone  on  treatment  identical  with  that  applied  to  the  fo's-triphenylmethyl- 
hydrazine,  it  was  concluded  that  if  any  phenylimido-benzophenone  was  formed  by  re- 
arrangement in  any  of  these  experiments,  it  was  exceedingly  minute  in  amount.  Traces 
of  aniline,  if  proved,  could  be  explained  by  the  presence  of  the  0.4  to  0.5  cc.  of  air  found 
to  be  occluded  by  the  zinc  chloride  and  freed  when  heated  as  described  above. 

The  hydrocarbon  extracted  from  the  distillate  with  steam  on  evaporation  of  the 
ether  proved  to  be  triphenylmethane  melting  at  88-90°,  while  the  steam  distillation 
residue  in  benzene  solution  yielded  triphenylmethane  crystals  which  after  being  washed 
with  ligroin  melted  at  88-89°. 

The  nitrogen  evolved  in  these  last  four  experiments  varied  from  50  to  75%  of  the 
total  nitrogen  in  the  sample  taken. 

Although  a  priori  reasons  make  it  unlikely  that  phenol  was  formed  in  these  ex- 
periments (see  the  introduction),  the  alkaline  sodium  zincate  solutions  from  the  fourth, 
fifth  and  sixth  experiments  were  saturated  with  carbon  dioxide  and  extracted  with  ether. 
The  extracts  were  allowed  to  evaporate  spontaneously.  The  residues  showed  no  test 
for  phenol  on  the  addition  of  ferric  chloride. 

These  results,  in  the  light  of  those  from  the  rearrangements  in  air, 
raise  the  rather  serious  question  as  to  whether  the  oxygen  of  the  air  is 
productive  of  the  rearrangement  or  whether  the  carbon  dioxide  exerts 
an  inhibitive  influence  on  it.  Qualitative  and  quantitative  determinations 
of  the  ammonia  in  the  products  of  the  attempted  rearrangements  in  carbon 
dioxide  will  show  whether  the  carbon  dioxide  prevents  completely  the 
primary  splitting  into  triphenyl-methylamine  and  the  univalent  nitrogen 
derivative  which  rearranges  to  give  benzophenone-phenylimide,  or  only 
prevents  this  latter  rearrangement  after  the  splitting  has  occurred.  If 
the  splitting  does  occur,  it  is  much  less  in  carbon  dioxide  than  in  air, 
in  view  of  the  amounts  of  nitrogen  and  of  the  hydrocarbon  products 
found.  It  is  considered  doubtful  that  the  splitting  occurs,  but  only  ex- 
perimental study  which  includes  data  oh  the  amounts  of  ammonia  formed 
can  determine  that.  With  data  available  on  the  rearrangement  in  an 
atmosphere  of  nitrogen  or  in  vacuo  a  quantitative  study  of  the  ammonia, 
aniline  and  phenol  as  well  as  the  other  products  from  rearrangements 
effected  in  mixtures  of  oxygen  and  nitrogen,  in  which  the  percentage  of 
oxygen  is  made  to  vary  from  zero  to  that  of  the  air,  should  shed  valuable 
light  on  the  true  part  oxygen  plays  in  the  rearrangement. 

Two  arrangements,  one  in  air  and  one  in  oxygen,  carried  out  simul- 
taneously in  the  same  metal  bath  and  with  a  lOOcc.  Erlenmeyer  flask 
gave  these  results. 

Time        Aniline  Phenol  Aniline 

Sample       ZnClz     Temp,     heated       found  found  calc. 

G.  G.         °C.          Sec.  G.  G.  G. 

Air 0.5192        7        450        70        0.0307        0.0279        0.0936 

Oxygen 0.5701         7        450        70        0.0307        0.0318        0.1028 

Because  of  difficulties  in  securing  exactly  duplicate  physical  conditions 


25 

conclusions  cannot  safely  be  drawn  on  less  than  a  whole  series  of  such 
measurements,  together  with  the  quantitative  determinations  of  the  am- 
monia produced  in  each  arrangement. 

Summary 
Our  conclusions  may  be  summarized  as  follows. 

1.  The  formation  of  an  aniline  derivative  by  the  rearrangement  of 
syw.-fos-triphenylmethylhydrazine,  as  observed  by  Senior  and  the  one  of 
us,  was  fully  confirmed. 

2.  Benzophenone  was  isolated  as  a  product  of  the  hydrolysis  of  the 
presumable  primary  rearrangement  product  phenylimido-benzophenone. 

3.  The  decomposition   products  of  triphenyl-methylamine,   namely, 
ammonia  and  diphenylene-phenylmethane  and  triphenylmethane,  which 
are  formed  when  triphenyl-methylamine  is  heated  with  zinc  chloride, 
were  also  found  in  quantity  in  the  reaction  products  and  the  conclusion 
drawn  that  triphenyl-methylamine  is  a  primary  product  of  the  action 
studied  and  is  then  decomposed  in  the  manner  indicated. 

4.  Triphenylmethane  and  nitrogen  were  proved  to  be  products  of  the 
thermal  decomposition  of  the  hydrazine,  the  result  of  an  intramolecular 
oxidation-reduction  in  a  direction  reverse  to  that  which  causes  the  re- 
arrangement. 

5.  Phenol  was  obtained  in  quantity  when  the  rearrangement  reaction 
was  carried  out  in  air  but  none  was  found  when  the  action  was  carried  out 
in  an  atmosphere  of  carbon  dioxide.     The  hypothesis  has  been  tentatively 
formulated  that  the  formation  of  phenol  is  due  to  the  capture  of  oxygen 
by  escaping  migrating  phenyl  radicals. 

•6.  In  support  of  this  view  the  sum  of  the  aniline  and  the  phenol  ob- 
tained was  found  to  be  roughly  equal  to  the  total  amount  of  ammonia 
formed. 

7.  The  observation  was  made  that  there  is  apparently  no  rearrange- 
ment in  the  absence  of  air,  a  result  which  demands  further  investigation 
of  the  possibility  that  the  rearrangement  is  the  result  of  an  oxidation  re- 
action in  which  the  oxygen  of  the  air  takes  part. 

8.  The  interpretation  of  the  reactions  from  the  point  of  view  of  the 
theory  of  electronic  valences  is  given  and  accords  well  with  the  explanation 
of  other  rearrangements  of  this  general  type. 


The  author  takes  this  opportunity  to  express  his  very  great  apprecia- 
tion of  the  kindly  interest  and  valuable  suggestions  of  Professor  Julius 
Stieglitz,  under  whose  direction  this  research  was  carried  out.  It  is  also 
his  desire  to  make  grateful  acknowledgment  of  the  material  aid  enjoyed 
during  his  encumbency  of  the  Swift  Fellowship. 


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